Study On The Energy Storage Performance Of PMMA-based Composite Thin Film Based On The Optimized Phase Structure Design Of BST

Compared with energy storage components such as traditional batteries and supercapacitors,dielectric capacitors have the advantages of higher power density and more cycle charging times,etc.,and they are commonly used as the core component of the electric vehicle inverter and the pulse power supply of the electromagnetic ejection system,the damping capacitor of the high-voltage DC transmission converter valve,and the DC support capacitor for photovoltaic or wind energy grid connection.At present,power devices and electronic devices are developing towards light weight and integration.Improving the energy storage performance of dielectric film capacitors has important scientific significance and engineering value for reducing energy loss and reducing engineering space.The relative dielectric constant and breakdown field strength of dielectric thin film materials are the key factors that directly determine the energy storage density of capacitors.It is an important means to optimize the energy storage performance of polymer films by compounding polymer with high breakdown and inorganic ceramic particles with high dielectric constant.However,most studies only focus on the influence of filler doping content,surface modification and other factors on the energy storage performance of composite films,and there is no systematic study on the effect of filler intrinsic properties on composite films.Based on this,this paper proposes to systematically analyze the effects of the filler phase composition,intrinsic electrical properties,doping content,and surface modification factors on the electrical properties of the composite film on the basis of fully studying the composition of the inorganic filler phase and its intrinsic electrical properties.In this paper,Bax Sr1-x Ti O3?Bx S1-x T?ceramic nanoparticles with a perovskite structure were selected as the inorganic filler phase and polymethyl methacrylate?PMMA?as the polymer matrix.Bx S1-x T ceramic powders with different phase compositions can be obtained by adjusting the barium-strontium ratio,then,Bx S1-x T ceramic powders?denoted as Bx S1-x T@S?with different Si O₂ coating thicknesses were obtained by changing the concentration of the precursor,and ceramic blocks were prepared by hot pressing sintering.The effects of phase composition and Si O₂ coating thickness on the intrinsic polarization behavior,dielectric properties and breakdown strength of Bx S1-x T ceramics were compared and analyzed.Studies have shown that compared to ferroelectric phase ceramics,paraelectric phase Bx S1-x T ceramics?x?0.6?have higher breakdown field strength and lower relative dielectric constant?x?0.7?.When the thickness of the Si O₂ package is about 8nm,the polarization strength and breakdown field strength of B_0.4S_0.6T@S ceramic can be taken into consideration.Compared with unwrapped ceramics,B_0.4S_0.6T@S ceramics have better insulation strength,but the relative dielectric constant is reduced to some extent.The B_xS_1-xT and B_xS_1-xT@S ceramic nano-powders with different phase compositions were blended into the PMMA matrix as an inorganic filler phase to prepare composite media with different doping contents.By characterizing the microstructure of the composite film and testing and analyzing the electrical properties of the composite film,the effects of doping content,surface modification,and intrinsic properties of the filler on the electrical properties of the composite film were systematically studied.Research shows that when the electric field strength is 490k V/mm,the energy storage density of 1 vol%B_0.6S_0.4T/PMMA composite dielectric with paraelectric phase structure filled phase reaches 12.2 J/cm³,which is improved25%compared to pure PMMA dielectric.The energy storage density of 1 vol%B_0.6S_0.4T@S/PMMA composite dielectric reaches 19.6 J/cm³,which is double that of pure PMMA media.Meanwhile,the energy storage efficiency of the composite dielectric under the maximum electric field is as high as 74.4%.